The present invention relates to a method for preparing cellulose ethers containing tertiary and quaternary nitrogen.
Cellulose ethers containing quaternary nitrogen are known from DE-OS No. 1 593 657 (U.S. Pat. No. 3,472,840) and are obtained according to the reaction conditions therein described by reacting cellulose with e.g. 2,3-epoxypropyl trimethyl ammonium chloride in organic solvents which can contain 0.2 to 5% water in relation to the cellulose.
Cationically modified cellulose derivatives are also described in JP-OS No. 53/90368 (CA 89 (22): 18 14 23 w). Here, a mixture of water, isopropyl alcohol and aqueous sodium hydroxide solution are used as the reaction medium.
The presence of an organic solvent which is largely inert under reaction conditions in relation to the etherification reagent is also especially advantageous according to De-OS No. 3 301 667. The cellulose is suspended in the organic solvent, the suspension thus formed is compounded with the aqueous solution of an alkali hydroxide and the etherification reagent subsequently added.
The reaction according to European Patent No. A-0189 935 also follows this pattern.
Water-soluble products are obtained in all the above specified instances which are separated after the neutralization, washed and dried.
The known methods entail the use of large amounts of organic solvent, small charge concentrations, low yields and also the loss of product due to its solubility in the reaction mixture.
The cellulose products modified in this manner are used in cosmetics (hair treatment), in textiles (softener, antistatic agents), in the paper industry, in flotation and flocculation and in drilling fluids. The uses of these cellulose products are well known in the art.